Abstract: A bulk acoustic wave spectrum analyzer and channelizer, using bulk acoustic wave beams in a body of material having the property of conducting bulk acoustic wave beams, including acoustically reflecting surfaces. An input transducer is positioned upon one surface of the body for launching acoustic beams into the body. At least one output transducer set, including a plurality of aligned, juxtaposed electrodes are placed on the outer surfaces of each of the output transducers of the transducer sets.

Abstract: An electronically tunable optical filter utilizing noncollinear acousto-optic interaction in a birefringent crystal. Light is diffracted by a secondary acoustic wave generated from a primary acoustic wave by mode conversion at an internal surface of the birefringent crystal. A preferred configuration is described in which the primary acoustic wave is excited by acoustical transducers bonded to the same face as the optical aperture. The configuration has the advantages of simpler construction and improved performance.

Abstract: A transverse configuration, electronically tunable acousto-optic filter assembly with improved spectral resolution and increased aperture. The crystal prism member is made of TeO.sub.2 and has a large prism angle (i.e., close to 90 degrees). An acousic prism coupler member made of material with low acoustic velocity (such as TeO.sub.2, AsS.sub.3, or GeAsSe), to avoid total internal reflection of the interface, is bonded in optical contact with a face of the crystal prism member which defines one extreme of the large prism angle, and which is not traversed by a polarized light beam that is transmitted through the crystal prism member and that interacts with a generated, perpendicularly directed, acoustic wave. The use of the acoustic prism couple member, togther with the use of a large prism angle in the crystal prism member, result in high spectral resolution and large aperture of the filter assembly and its desired useability in the infrared region.

Abstract: An acoustic resonant structure for use in a tunable acousto-optic filter to reduce drive power requirements. The undesirable ripples in the tuning bandpass response due to acoustic resonance is minimized by reducing the effective finesse of the filter.

Abstract: An electronically tunable optical filter using acousto-optic interaction in a dispersive birefrigent crystal. The strong wavelength dispersion of birefringence in a class of uniaxial semiconductors near the band gap is utilized to enhance the spectral resolution of the tunable acousto-optic filter. The dispersive tunable acousto-optic filter provides a very large aperture while maintaining an extremely narrow bandwidth.

Abstract: An electronically tunable optical filter utilizing noncollinear acousto-optic interaction in a birefringent crystal. The directions of optical and acoustic waves are chosen so that large angular aperture is obtained for an interaction geometry wherein the light beam is perpendicular to the group velocity of the acoustic wave. The transverse configuration provides maximum optical aperture for the tunable acousto-optic filter.

Abstract: The intensity of light beams transmitted through a tunable acousto-optic modulator is controlled by modulating the center wavelength of the filter passband. Such wavelength modulation can be obtained by modulation of the acoustic frequency or the crystal birefringence. An acousto-optic modulator of this type is sensitive to the temporal coherence of the light beam. When used in an optically coherent detection system, it can provide detection of very weak laser beams in the presence of strong incoherent background radiations.

Abstract: An acousto-optic deflector that utilizes second order diffraction in a birefringent crystal provides doubled resolution while maintaining high diffraction efficiency. For the second order birefringent deflector employing a paratellurite crystal, 1200 spot resolution was achieved with a 24 MHz bandwidth and 25 .mu. sec access time. This maximum number of spots is twice that obtainable in a conventional first order acousto-optic deflector.

Abstract: An electronically tunable optical filter is described wherein an optical beam is diffracted by an acoustic beam the group velocity of which is noncollinear with the optical beam transmitted through the birefringent crystal medium. The frequency and the direction of the phase velocity of the acoustic wave are chosen for a given incidence direction of the optical beam so that the diffraction occurs for a band of optical frequencies centered about a predetermined optical frequency and a relatively large angular distribution of incident optical beams.